<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <!-- 实际开发都是外部样式表.适合于样式比较多的情况.核心是:样式单独写到CSS文件中，之后把CSS文件引入到HTML页面中使用. -->
    <div>
        123456
    </div>
</body>
</html>